Question

The density of a gas is $0.002\text{g/mL}$ at STP. Its molar mass is:

• A. $448\text{g/mol}$
• B. $44.8\text{g/mol}$
• C. $22.4\text{g/mol}$
• D. $224\text{g/mol}$

Answer 1

The correct option is B $44.8\text{g/mol}$

Given,
$\text{Density of gas at STP}=0.002\text{g/mL}$
$\therefore \text{Mass of}1\text{mL}=0.002\text{g}$
$\text{At STP}22400\text{mL}\text{contains 1 mole of the gas}$.
$\text{Mass of}22400\text{mL}=\text{molar mass of the gas}$
$=0.002\times 22400$
$=44.800\text{g/mol}$